Posterior Pelvic Injury : Wheeless' Textbook of Orthopaedics

- See:
- Malgaigne Fracture
      - Sacral Fractures
      - Sacroiliac Fracture Dislocations
             - cresent fracture

- Evaluation of Stability:
- as noted by Kellam, et al. (1987), a stable injury is one that can withstand normal physiologic forces w/o excessive deformation;
- it is also noted, however, that there are some unstable posterior injuries that have a high potential for healing (sacral frx) and
                   others with a lower potential for healing (? somewhat similar to bony Chance frx);
- physical exam:
- evaluation under flouro:
- determine whether there is gross motion in any of the three planes (medial-lateral, AP, and cephalad-caudad) and determine
                 whether there is rotational instability;
- manual palpation may reveal a movable & therefore unstable hemipelvis, hemipelvic fragments were presumably partially
                 reduced in supine position, which is suspicious, but nondiagnostic, of pelvic instability;
- this group of pts may have only partial ligament damage;
- this group of pts may show displacement of x-rays on f/u films;
     - ref: The unstable pelvic fracture. Operative treatment.

- Stability of Specific Injury Types:
- sacral frx:
- stable frx includes impacted vertical frx of sacrum, nondisplaced frx of posterior sacroiliac complex, and/or subtle frx of upper
                   sacrum as seen by asymmetry of sacral arcuate lines;
- unstable frx, is characterized by frx diastasis of more than 0.5 to 1 cm, along w/ an unstable anterior injury;
- vertical instability of hemipelvis: > 0.8 cm;
- caused by disruption of ventral sacroiliac, sacrospinous, & sacrotuberous ligaments as well as complete disruption of posterior
                    sacroiliac ligaments, w/ cephalad displacement of hemipelvis of > 0.5 to 0.8 cm;
- use outlet view for evaluation;
- anterior-posterior instability:
- disruption of ventral sacroiliac, sacrospinous, & sacrotuberous ligaments, & is represented by SI joint diastasis of > 1 cm;
- some consider diastatic frx of osseous components of posterior sacroiliac complex > 0.5 cm as unstable;
- note that an unstable frx may partially reduced in supine position;
- best seen on inlet view showing posterior displacement of sacrogluteal line, and is best confirmed by CT scan;
- rotational instability:
- lateral compression injury:
- unstable to internal rotation but is stable to external rotation (and actually reduces in external rotation);
- AP compression injuries:
- unstable to external rotation, but stable to internal rotation of the pelvis;
- rotational instability may be controled w/ external fixation;
- transverse process frx: (usually 5th lumbar);
- may be a minor sign of instability in about 20% of pts;
- even if these patients are found to have frx stability, many will have an ileus due to the severity of the trauma;
- anterior pelvic injury:
- generally pubic rami fractures will not require fixation followig fixation of the posterior pelvis, where as pubic
                    ramus disruption greater than 2.5 cm will require fixation;

- CT scan:
- useful in determining those whose initial x-ray appearance suspicious of instability and a clinical impression of stable pelvic
fracture;

- PreOp Planning:

- combined anterior & posterior unstable lesions:
- often cannot be approached simultaneously thru same incision, and rather it is necessary to stage the operation;
- in majority of cases, posterior lesion is approached first;
- following posterior internal fixation, an x-ray may show anterior reduction;
- w/ posterior injury + symphysis dislocation:
               - symphysis dislocation may be reduced & fixed first if there are no associated fractures thru pubic rami or acetabulum;
               - symphysis reduction may provide a partial reduction of pelvic ring followed by completion of reduction & fixation
                          posteriorly;
- combined posterior & unstable acetablar frx:
- reduction & internal fixation of posterior pelvic ring disruptions is performed prior to acetabular reduction whether posterior
               ring disruption is ipsilateral or contralateral;
- pelvic ring distortion may make the acetabular frx impossible to reduce;
- type of acetabular frx may dictate surgical approach for posterior pelvic lesion;
- in case of SI dislocation assoc w/ anterior column frx both injuries are approached thru ilioinguinal approach;
- SI joint can be approached thru extended iliofemoral approach or by extending Kocher-Langenbeck approach;

- Choice of Incisions:
- choice of incision depends on assoc injuries, soft tissue contussion, abrasion, laceration, or hematoma cavities, as well as supra
pubic catheters;
- most posterior injuries can be assessed thru posterior surgical incision;
- posterior approach (Kocher Langenbock):
- anterior approach to SI joint:

- Choice of Hardware:
- orthomed pelvic reduction clamps
- percutaneous SI joint fixation
- indicated for sacroiliac fracture dislocations and for some sacral fractures;

    - transiliac sacral bars:
- utilizes Harrington rods, w/ compression achieved by tightening of threaded nuts;
- advantages include technical ease of insertion and limited soft tissue dissection;
- relative contraindications include iliac wing fractures;
- cautions: may cause over compression of sacral fractures;
           - see synthes technique guide
- 4.5 mm reconstruction plate: (Albert et al (1993))
           - indicated for posterior pelvic fractures as well as sacral fractures;
- reconstruction plate is placed along dorsum of the sacral and thru the posterior iliac spines (transiliac plate fixation);
- advantages:
- low profile, minimal risk to N/V structures, and no need for flouro;
- patient is placed in the prone position;
- two incisions are made over the PSIS which are perpendicular to the iliac wings, and one vertical incision is made over the
                  base of the S1 spinous process;
- dissections are caarried down to the bony surfaces;
- predrill the PSIS to assist w/ reconstruction plate insertion;
- use the 4.5 drill to make 2-3 drill holes 1 cm lateral to the PSIS;
- an appropriately sized 4.5 mm reconstruction plate is chiseled thru the iliac spine, passed along the dorsum of the sacrum to
                  the opposite PSIS;
- the recon plate is appropriately contoured;
- the plate is fixed to the iliac wings using 6.5 mm cancellous screws, w/ two screws inserted into each ilac wing;
- postop: patients can be bed to chair or touch down wt bearing;
- ref:
- Posterior Pelvic Fixation Using a Transiliac 4.5 mm Reconstruction Plate: A clinical and biomechanical study.